This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-099760, filed Mar. 31, 2000, the entire contents of which are incorporated herein by reference.
This invention relates to a method for manufacturing a semiconductor device by means of dry etching. In particular, the present invention relates to a method of forming a mask to be used for working an underlying layer, and to a method of etching by making use of the mask. This invention also relates to a semiconductor device to be formed by making use of this etching method.
Today, there is an increasing demand to further miniaturize the pattern of semiconductor elements due to an increasing integration of the semiconductor devices. Further, in view of further accelerating the response speed of the semiconductor devices, there has been tried to reduce the wiring resistance or the parasitic resistance of wiring. Meantime, the patterning of photoresist film has been performed by making use of a reflection preventive film which is formed directly below the photoresist film.
A dual damascene work is now extensively adopted in the technique of manufacturing a semiconductor device, wherein wiring grooves and contact holes associated with the wiring grooves are formed in an interlayer insulating film, and then, metallic wirings and contact plugs were buried in these grooves and holes, respectively. There are two possible alternative methods for carrying out the dual damascene work, i.e. a method wherein the contact holes are formed at first, and then, the wiring grooves are formed so as to overlap the contact holes (holes first, grooves later), and a method wherein the wiring grooves are formed at first, and then, the contact holes are formed therein (grooves first, holes later).
In the method where the wiring grooves are formed in advance in the aforementioned manufacturing method of semiconductor device, since the patterning of the contact holes are performed after the working of wiring grooves, the DOF (Depth of Focus) is caused to decrease due to the influence of the step portion of the grooves, so that as the patterning size decreases, it becomes increasingly difficult to perform a satisfactory patterning. On the other hand, in the method where the contact holes are formed in advance, since the patterning of the wiring grooves are performed after the working of contact holes, a reflection preventive film and a resist (photoresist) are caused to enter into the contact holes.
Meantime, since the resist film is required to be formed thinner in conformity with the increasing miniaturization of semiconductor device today, it is indispensable to secure a high etching selectivity between the resist film and an interlayer insulating film on the occasion of the etching work of the wiring grooves. Therefore, the reflection preventive film and the resist that have been entered into the contact holes act as a mask for the sidewalls of contact holes, thereby giving rise to the generation of residue of the interlayer insulating film on the surface of contact holes on the occasion of forming the wiring grooves. This generation of residue of the interlayer insulating film leads to a deterioration of reflow characteristics of the wiring material, and also to a cause for giving a bad influence to the electric characteristics of semiconductor device.
Further, in a situation where a portion of a semiconductor chip is subjected to a dual damascene work, and the other portion thereof is subjected to the work for forming the contact holes of high aspect ratio, since the patterning in the dual damascene work is required to be repeated at least twice, the misregistration of lithography is liable to be generated in the operation of forming the contact holes of high aspect ratio at the aforementioned other portion of the semiconductor chip. Additionally, a reflection preventive film and a resist may enter into the contact holes on the occasion of the second patterning process, thereby allowing the resist to act as a mask to make it difficult to satisfactory perform the working.
As the wirings to be formed in a semiconductor device becomes increasingly finer, the width between wirings becomes increasingly narrower. As a result, the wiring resistance is caused to increase, thereby raising the problem that the propagation velocity of signals becomes lower. As explained above, in the case of the dual damascene work, as the pattern to be formed therein becomes increasingly finer, the resist film is also required to be thinner, so that the etching is required to be performed using an interlayer insulating film having a higher etching selectivity relative to the resist film. As a result, the residue of the interlayer insulating film is caused to remain on an upper portion of contact holes on the occasion of forming the wiring grooves. This residue of the interlayer insulating film leads to a deterioration of reflow characteristics of the wiring material, and also to a cause for deteriorating the electric characteristics of semiconductor device.
In a situation where a pattern is desired to be formed on each of different kinds of film (mixed films) which have been formed in advance on the surface of a semiconductor chip, i.e. an interlayer insulating film has been formed on a portion of the surface of the semiconductor chip, while a polysilicon film has been formed on another portion of the surface of the semiconductor chip, the pattern-forming process including patterning and RIE is required to be separately performed for each kind of films, resulting in an increase in the number of steps and in deterioration of productivity.
Further, in order to make it possible to perform the fine working of a semiconductor, a reflection preventive film is formed prior to the step of forming a pattern using a resist on the occasion of working an insulating film or a metallic film. In this case, since the portion where wirings are densely located (densified portion) differs in terms of DOF (Depth of Focus) from the portion where wirings are sparsely located (sparse portion), if an isolated wiring is to be formed, the densified portion would be under-dosed, thereby rendering the wiring of this densified portion to become tapered in cross-section. On the other hand, if wirings of high-density is to be formed, the sparse portion would be over-dosed, thereby leading to the generation of skipping of pattern where the pattern in the sparse portion is failed to be formed.
This invention has been achieved under the circumstances mentioned above, and therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device, which is capable of excellently controlling the various shapes of patterns which differ depending on the region in a semiconductor chip.
Another object of the present invention is to provide a semiconductor device having precise patterns formed therein.
A still another object of the present invention is to provide a method of manufacturing a semiconductor device, which enables patterns to be worked with excellent controllability even if a film having different kinds of underlying layer is formed thereon.
Namely, the present invention is featured in that the work to form a resist mask is performed after a hard mask layer is subjected to the masking work thereof, thereby incorporating all of the hard mask into the resist; or in that the region where the resist mask exists is formed at a portion of a semiconductor chip, and the region where the hard mask exists is formed at another portion of the semiconductor chip. As a result, it becomes possible to excellently control the various shapes of patterns which differ depending on the region in a semiconductor chip, and to enable patterns to be worked with excellent controllability even if a film having different kinds of underlying layer is formed thereon.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film or a metal film on a surface of a semiconductor substrate; forming at least two kinds of mask on a surface of the insulating film or the metal film; and performing a plurality of etching works to the insulating film or the metal film in conformity with the various kinds of mask.
In the manufacturing method according to the first aspect of the present invention, the at least two kinds of mask may be a hard mask and a carbon-containing mask, respectively.
In the manufacturing method according to the first aspect of the present invention, wherein the at least two kinds of mask are a hard mask and a carbon-containing mask, respectively, the hard mask may be covered with the carbon-containing mask.
In the manufacturing method of according to the first aspect of the present invention, wherein the at least two kinds of mask are a hard mask and a carbon-containing mask, respectively, when the insulating film is to be worked, the hard mask to be employed may be formed of an insulating film which is different from the first mentioned insulating film or a metal film; and when the metal film is to be worked, the hard mask to be employed may be formed of an insulating film.
In the manufacturing method of according to the first aspect of the present invention, wherein the at least two kinds of mask are a hard mask and a carbon-containing mask, respectively, the carbon-containing film may be formed of a material selected from the group consisting of a resist, a low dielectric constant insulating film, and carbon film.
According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film or a metal film on a surface of a semiconductor substrate; forming a hard mask on a surface of the insulating film or the metal film; forming a carbon-containing film on the insulating film or the metal film having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film, the resultant pattern of the carbon-containing film being subsequently employed as a mask to perform a first etching work of the insulating film or the metal film; and removing the patterned carbon-containing film, which is followed by a second etching work of the insulating film or the metal film with the hard mask being employed as a mask.
In the manufacturing method according to the second aspect of the present invention, a metal film or a film of insulating material which differs from the insulating film may be buried in the insulating film to be subjected to the etching work.
In the manufacturing method according to the second aspect of the present invention, the process of patterning the carbon-containing film may comprise the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask.
In the manufacturing method according to the second aspect of the present invention, wherein the process of patterning the carbon-containing film comprises the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask, the patterning process may further comprise a step of forming a reflection preventive film on the SOG film.
According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the insulating film, and patterning the film of hard mask to obtain a hard mask; forming a carbon-containing film on the insulating film having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to remove part of the carbon-containing film which is located in a first region of the semiconductor substrate to thereby obtain a patterned carbon-containing film which is located in a second region of the semiconductor substrate, thereby forming a mask; subjecting the insulating film to a first etching work with the hard mask of the first region and the mask of the second region being employed as a mask; removing the carbon-containing film located in the second region; and subjecting the insulating films of the first and second regions to a second etching work with the hard mask being employed as a mask.
In the manufacturing method according to the third aspect of the present invention, the hard mask may be formed of a film of an insulating material which is different from the insulating film or a metal film.
In the manufacturing method according to the third aspect of the present invention, the carbon-containing film may be formed of a material selected from the group consisting of a resist, a low dielectric constant insulating film, and carbon film.
In the manufacturing method according to the third aspect of the present invention, a metal film may be buried in the insulating film to be subjected to the etching work.
In the manufacturing method according to the third aspect of the present invention, the process of patterning the carbon-containing film may comprise the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask.
In the manufacturing method according to the third aspect of the present invention, wherein the process of patterning the carbon-containing film comprises the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask, the patterning process may further comprise a step of forming a reflection preventive film on the SOG film.
In the manufacturing method according to the third aspect of the present invention, the manufacturing method may further comprise a step of burying a metal film in the wiring grooves and contact holes which are formed in the first and second etching works.
According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming a first insulating film on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the first insulating film, and patterning the film of hard mask to obtain a hard mask; forming a carbon-containing film on the first insulating film having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to form a mask; subjecting the first insulating film to a first etching work with the mask of carbon-containing film being employed as a mask; removing the mask of carbon-containing film; subjecting the first insulating film to a second etching work with the hard mask being employed as a mask; burying a metal film in the wiring grooves provided with contact holes and in the contact holes which are formed in the first and second etching works; forming a second insulating film on the first insulating film in which the metal film is buried; forming wiring grooves in the second insulating film, the wiring grooves allowing prescribed contact plugs that have been formed in the first insulating film to expose; and burying metal wirings in the wiring grooves formed in the second insulating film.
In the manufacturing method according to the fourth aspect of the present invention, the patterning may be performed in a manner to allow the wiring grooves and the contact holes to be disposed alternately.
In the manufacturing method according to the fourth aspect of the present invention, the carbon-containing film may be formed of a material selected from the group consisting of a resist, a low dielectric constant insulating film, and carbon film.
In the manufacturing method according to the fourth aspect of the present invention, the process of patterning the carbon-containing film may comprise the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask.
In the manufacturing method according to the fourth aspect of the present invention, wherein the process of patterning the carbon-containing film comprises the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask, the patterning process may further comprise a step of forming a reflection preventive film on the SOG film.
According to a fifth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film on a surface of a semiconductor substrate; forming a metal film in a predetermined region of the insulating film; forming a film of hard mask on the surfaces of the insulating film and the metal film, and patterning the film of hard mask to obtain a hard mask; forming a carbon-containing film on the insulating film and the metal film each having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to form a mask; subjecting the insulating film to a first etching work with the mask of carbon-containing film being employed as a mask; removing the mask of carbon-containing film; and subjecting the insulating film and the metal film to a second etching work with the hard mask being employed as a mask.
In the manufacturing method according to the fifth aspect of the present invention, a metal film may be buried in the insulating film to be subjected to the etching work.
According to a sixth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film or a metal film on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the insulating film or the metal film, and patterning the film of hard mask to form a hard mask in a region where a sparse pattern is to be formed or in a region where a dense pattern is to be formed; forming a carbon-containing film on a surface of the insulating film or the metal film where the hard mask is not formed, which is followed by a patterning work of the carbon-containing film to form a mask in the region where a sparse pattern is to be formed or in the region where a dense pattern is to be formed; and subjecting the insulating film or the metal film to an etching work with the hard mask and the mask being employed as a mask.
In the manufacturing method according to the sixth aspect of the present invention, a metal film or a film of insulating material which differs from the insulating film may be buried in the insulating film to be subjected to the etching work.
According to a seventh aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the insulating film, and patterning the film of hard mask to form a hard mask in a region where wirings are to be sparsely patterned or in a region where wirings are to be densely patterned; forming a carbon-containing film on the insulating film having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to form a mask in the region where wirings are to be sparsely patterned or in the region where wirings are to be densely patterned; subjecting the insulating film to an etching work with the hard mask and the mask being employed as a mask, thereby forming wiring grooves; removing the hard mask and the mask; forming wirings of dense pattern region or of sparse pattern region in the wiring grooves in a region where the hard mask is formed, and at the same time, forming wirings of dense pattern region or of sparse pattern region in the wiring grooves in a region where the mask is formed.
In the manufacturing method according to the seventh aspect of the present invention, in a case where the insulating film is to be worked, the hard mask may be formed of an insulating film which differs in kind from the first mentioned insulating film.
In the manufacturing method according to the seventh aspect of the present invention, the carbon-containing film may be formed of a material selected from the group consisting of a resist, a low dielectric constant insulating film, and carbon film.
In the manufacturing method according to the seventh aspect of the present invention, the process of patterning the carbon-containing film may comprise the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask.
In the manufacturing method according to the seventh aspect of the present invention, wherein the process of patterning the carbon-containing film comprises the steps of: successively forming an SOG film and a resist film on a surface of the carbon-containing film; patterning the resist film, and working the SOG film with the patterned resist film being employed as a mask; and etching the carbon-containing film with this worked SOG film being employed as a mask, the patterning process may further comprise a step of forming a reflection preventive film on the SOG film.
According to an eighth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming a film of gate electrode on an insulating film formed on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the film of gate electrode, and patterning the film of gate electrode to form a hard mask in a region where gate is designed to be sparsely formed or in a region where gate is designed to be densely formed; forming a carbon-containing film on the film of gate electrode having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to form a mask in a region where gate is designed to be sparsely formed or in a region where gate is designed to be densely formed; subjecting the film of gate electrode to an etching work with the hard mask and the mask being employed as a mask, thereby forming a dense gate region or a sparse gate region in the film of gate electrode in a region where the hard mask is formed, and at the same time, forming a dense gate region or a sparse gate region in the film of gate electrode in a region where the mask is formed.
According to a ninth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises the steps of: forming an insulating film on a surface of a semiconductor substrate; forming a film of hard mask on a surface of the insulating film, and patterning the film of hard mask to form a hard mask in a region where an element isolation region is designed to be sparsely formed or in a region where an element isolation region is designed to be densely formed; forming a carbon-containing film on the insulating film having the hard mask formed thereon, which is followed by a patterning work of the carbon-containing film to form a mask in a region where the element isolation region is designed to be sparsely formed or in a region where the element isolation region is designed to be densely formed; subjecting the insulating film to an etching work with the hard mask and the mask being employed as a mask, thereby forming grooves in the semiconductor substrate; removing the hard mask and the mask; burying the element isolation film of dense pattern region or the element isolation film of sparse pattern region in the grooves of a region where the hard mask is formed, and at the same time, burying the element isolation film of dense pattern region or the element isolation film of sparse pattern region in the grooves of a region where the mask is formed.
According to a tenth aspect of the present invention, there is provided a semiconductor device which comprises: a semiconductor substrate; a first metallic wiring layer buried in a first insulating film which has been formed on the semiconductor substrate; and a second metallic wiring layer buried in a second insulating film which has been formed on the first insulating film and electrically connected via a contact plug with the first metallic wiring layer; wherein a top surface of a prescribed wiring constituting the second metallic wiring layer is disposed higher than a top surface of another wiring constituting the second metallic wiring layers placed on both sides of the first mentioned second metallic wiring layer.
According to an eleventh aspect of the present invention, there is provided a semiconductor device which comprises: a semiconductor substrate; a first metallic wiring layer buried in a first insulating film which has been formed on the semiconductor substrate; and a second metallic wiring layer buried in a second insulating film which has been formed on the first insulating film and electrically connected via a contact plug with the first metallic wiring layer, the second metallic wiring layer being constituted by a plurality of parallel wirings; wherein top surfaces of a plurality of wirings constituting the second metallic wiring layer are disposed higher than a top surface of another wiring constituting the second metallic wiring layers placed on both sides of the first mentioned second metallic wiring layer.